Obama spoke at a news conference with Singapore Prime Minister Lee Hsien Loong inside the White House and uttered his harshest remarks yet about the New York billionaire.

He urged Republicans to withdraw support for their party’s presidential pick, saying he is “woefully unprepared to do this job.”

Obama added: “The question they have to ask themselves is: If you are repeatedly having to say in very strong terms that what he has said is unacceptable, why are you still endorsing him?”

The 44th president also pointed out Trump’s lack of knowledge and depth in handling international duties.

“This isn’t a situation where you have an episodic gaffe. This is daily,” Obama said. “There has to be a point at which you say, this is not somebody I can support for president of the United States, even if he purports to be a member of my party. The fact that that has not yet happened makes some of these denunciations ring hollow.”

Trump said: “They have shipped millions of our best jobs overseas to appease their global special interests. They have betrayed our security and our workers, and Hillary Clinton has proven herself unfit to serve in any government office.”

Obama's comments come less than a week after his DNC speech where he took jabs at Trump's rhetoric and policies.

“The Donald is not really a plans guy. He’s not really a facts guy, either,” Obama said. “He calls himself a business guy, which is true, but I have to say, I know plenty of businessmen and women who’ve achieved remarkable success without leaving a trail of lawsuits, and unpaid workers, and people feeling like they got cheated.”